摩尔浓度计算器 — 计算浓度、摩尔数 & 体积
Use the molarity formula M = n / V to solve for concentration (mol/L), moles of solute, or volume of solution. Enter any two values and this calculator instantly computes the third. The built-in mass-to-moles helper converts grams to moles using molar mass, with one-click presets for common lab compounds including NaCl, NaOH, HCl, H₂SO₄, and glucose.
Molarity Calculator
Mass to Moles Helper
Convert mass (grams) to moles using molar mass, then auto-fill the moles field above.
Frequently Asked Questions
什么是摩尔浓度（Molarity）？
摩尔浓度（M）是溶液中溶质的物质的量浓度，单位为 mol/L（摩尔/升），表示每升溶液中含有多少摩尔溶质。公式为：M = n / V，其中 n 是溶质的物质的量（mol），V 是溶液体积（L）。
如何配制特定摩尔浓度的溶液？
①计算所需溶质质量：m = M × V × 摩尔质量；②称取相应质量的溶质；③溶于少量溶剂中充分溶解；④转移至容量瓶，加溶剂至刻度线，摇匀。例如，配制 1L 1M NaCl 溶液需 58.44g NaCl（摩尔质量 58.44 g/mol）。
摩尔浓度和质量浓度有什么区别？
摩尔浓度（mol/L）以物质的量为基准，便于化学计量计算；质量浓度（g/L 或 mg/mL）以质量为基准，便于实际配制。两者换算：质量浓度 = 摩尔浓度 × 摩尔质量。
什么是标准溶液？
标准溶液是已知精确浓度的溶液，用作分析化学中的基准。一级标准物质（如草酸、碳酸钠）可直接称量配制；二级标准物质（如 NaOH、HCl）需通过标定（与已知浓度溶液反应）来确定精确浓度。
Molarity Formula
Molarity (M) is the most common unit for expressing solution concentration in chemistry and biology. It describes the number of moles of solute dissolved per liter of solution. This calculator solves for any one of the three related variables — molarity, moles, or volume — when the other two are known.
How to Calculate Molarity
M = n / V
Rearranging the formula gives:
- n = M × V — to find moles when molarity and volume are known
- V = n / M — to find volume when moles and molarity are known
How to Use This Calculator
- Select what you want to solve for: Molarity, Moles, or Volume.
- Enter the two known values in the input fields.
- The result appears instantly — all three values are shown together.
- Optionally use the Mass to Moles Helper if you know the mass and molar mass of your solute instead of the number of moles directly.
Mass to Moles Conversion
In most lab scenarios you weigh out a solid on a balance, so you have mass in grams rather than moles. Convert grams to moles using:
n = m / Mr
n = moles | m = mass (g) | Mr = molar mass (g/mol)
The helper section in the calculator lets you enter the mass and select from common compounds (or type any molar mass), then click "Use this value" to auto-fill the moles field.
Common Molar Masses
The molar mass of a compound equals the sum of the atomic masses of all atoms in one formula unit.
| Compound | Formula | Molar Mass (g/mol) |
|---|---|---|
| Sodium chloride | NaCl | 58.44 |
| Sodium hydroxide | NaOH | 40.00 |
| Hydrochloric acid | HCl | 36.46 |
| Sulfuric acid | H₂SO₄ | 98.08 |
| Glucose | C₆H₁₂O₆ | 180.16 |
| Water | H₂O | 18.015 |
| Potassium chloride | KCl | 74.55 |
| Calcium chloride | CaCl₂ | 110.98 |
| Acetic acid | CH₃COOH | 60.05 |
| Ethanol | C₂H₅OH | 46.07 |
Molarity vs Molality
Molarity and molality are both measures of concentration but they differ in what the denominator refers to:
Molarity (M)
Moles of solute per liter of solution. Depends on temperature because liquid volume expands with heat. Most common in volumetric analysis and lab reagent preparation.
M = n / Vsolution
Molality (m)
Moles of solute per kilogram of solvent. Temperature-independent because mass does not change with temperature. Preferred in boiling point elevation and freezing point depression calculations.
m = n / kgsolvent
For dilute aqueous solutions at room temperature, molarity and molality are numerically similar because the density of water is approximately 1 kg/L.
Related Tools
- Dilution Calculator — Calculate C₁V₁ = C₂V₂ dilutions. Find the volume or concentration after diluting a stock solution.
- mEq to mg Calculator — Convert between milliequivalents and milligrams for electrolytes and ionic compounds.